Releasable hook

ABSTRACT

In the mooring of ships and boats to a dock, it is necessary to have a line run from the ship or boat to the dock. The line can be more or less tight and must be fixed so as to allow relatively little movement of the ship or boat with respect to the dock. Then, when it is necessary to allow the ship or boat to sail away from the dock, it is necessary to disengage the line from the fastening means on the dock. This invention relates to a fastening means whereby a line can be positioned to the fastening means for securing the ship or boat adjacent to the dock. Then, the person on the dock can mechanically actuate the fastening means to allow the line to slip away from the fastening means and also to allow the ship or boat to sail away from the dock. This fastening means is identified as a releasable hook. When it is desired to have the ship or boat fixedly secured with respect to the dock, the fastening means tend to disfunction. Then, when it is desired to allow the line to be slipped and to allow the ship or boat to sail away from the dock, the operator on the dock can quickly and easily disengage the fastening means, or releasable hook, from the line.

United States Patent 1191 Epstein 51 Sept. 25, 1973 RELEASABLE HOOK Irving Epstein, 4216 Shoreclub Dr., Mercer Island, Wash. 98040 [22] Filed: Dec. 22, 1969 [21] Appl. No.: 886,902

[76] Inventor:

Primary Examiner-Harvey C. Hornsby Assistant Examiner-Merle F. Maffei Att0rneyThomas W. Secrest [57] ABSTRACT In the mooring of ships and boats to a dock, it is necessary to have a line run from the ship or boat to the dock. The line can be more or less tight and must be fixed so as to allow relatively little movement of the ship or boat with respect to the dock. Then, when it is necessary to allow the ship or boat to sail away from the dock, it is necessary to disengage the line from the fastening means on the clock. This invention relates to a fastening means whereby a line can be positioned to the fastening means for securing the ship or boat adjacent to the dock. Then, the person on the dock can mechanically actuate the fastening means to allow the line to slip away from the fastening means and also to allow the ship or boat to sail away from the dock. This fastening means is identified as a releasable hook. When it is desired to have the ship or boat fixedly secured with respect to the dock, the fastening means tend to disfunction. Then, when it is desired to allow the line to be slipped and to allow the ship or boat to sail away from the dock, the operator on the dock can quickly and easily disengage the fastening means, or releasable hook, from the line.

8 Claims, 7 Drawing Figures PAIENImPzsmn SHEET 3'0? F1: [5. El

INVENTOR. '6 :EPSTIEAI ATTORNEH V RELEASABLE HOOK An object of this invention is to provide a positive catch for a line running from a ship or boat to the dock and also a positive release for said catch; a further object is to provide a mechanical, releasable hook which can be manually operated; a still further object is to provide a releasable hook having relatively few parts or components; a still further object is to provide a releasable hook having relatively few moving parts; another object is to provide a releasable hook which can be easily operated so as to quickly allow the releasable hook and the like to disengage; a still further object is to provide a releasable hook having a completely closed position, a fully open position, and an intermediate position between the completely closed position and the fully open position; and, a still further object is to provide a releasable hook which is inexpensive to manufacture.

These and other important objects and advantages of the invention will be more particularly brought forth upon reference to the accompanying drawings, the detailed description of the invention, and the claims.

In the drawings:

FIG. 1 is a side elevational view of the releasable hook, with portions broken away, to show in detail the mechanical linkage of the moving parts of said releasable hook;

FIG. 2, taken on line 22 of FIG. 1, is a lateral crosssectional view illustrating the relationship of the crosshead and the mounting bracket;

FIG. 3, taken on line 3-3, is a lateral fragmentary view illustrating the relationship of the U-shaped hook, the rotatable catch, the rotatable lever, the piston and the plungers with respect to the frame for definitely positioning the U-shaped hook with respect to the frame;

FIG. 4 is a fragmentary view illustrating the releasable hook in a fully open position and with the U- shaped hook rotated away from the frame so as to allow the line to quickly disengage from the U-shaped hook;

FIG. 5, taken on line '5--5, is a longitudinal cross sectional view of the rotatable lever, thelongitudinal passageway in the lever, the piston and pin in said longitudinal passageway, and the two plungers used for locking the position of the rotatable lever with respect to the frame;

' FIG. 6, taken on line 66 of FIG. 4, is a lateral crosssectional view illustrating the frame, the rotatable surface 36 on its end but on its outer surface near the end 36, has a slight curving surface 38. The leg upon going from the outer straight surface 36 to the base 32 becomes wider and of a heavier construction.

The U-shaped hook 26 is positioned between the two spaced apart plates 12 and 14 by means of a bolt which extends through aligned passageways in the plates 12 and 14 and also extends through aligned passageway 42 in the base 32 of said hook 26. There is a nut on the end of the bolt 40 to firmly position the plates 12 and 14 and the book 26.

Between the plates 12 and 14 and near the lower edge of these plates, and also in the base 16 of these catch and the linkage from the rotatable catch to the rotatable lever; and,

FIG. 7, taken on line 77 ofFIG. 4, is a fragmentary lateral cross-sectional view of the base of the lever and illustrates the linkage connecting with the rotatable catch, the longitudinal passageway in the lever, the piston in the rotatable lever when the releasable hook is fully open, and the two plungers bearing against the inner surfaces of the frame.

This invention is for a releasable hook 10 having two spaced apart plates 12 and 14. Each of these two spaced apart plates 12 and 14, see FIGS. 1 and 4, has a main body portion 16, a lower end 18 and an upper end 20. The upper end 20 has a curved upper shoulder 22 and a straight end 24. The lower end 18 is of a generally curved or circular configuration.

There is also a U-shaped hook 26 having a first leg 28 and a second leg 30. The U-shaped hook 26 has a base 32. The first leg 28 has a substantially flat surface 34 on its end. The second leg 30 has a substantially flat plates and somewhat closer to the end 18 than the end 20, there is a bolt 46 and which bolt extends through aligned passageways in the two plates 12 and 14. This bolt positions a rotatable catch 48 and which catch 48 can rotate around the bolt 46. The rotatable catch 48 is generally of flat stock having a recess 50. The recess 50 has an upper surface 52, a back surface 54, and a lower curving surface 56. The lower curving surface 56 generally mates with the outer surface 38 of the U- shaped hook 26, when the releasable hook is completely closed, see FIG. 1, and also when the releasable hook is partially closed or partially open, see the phantom lines of FIG. 1. Naturally, on the bolt 46 there is a nut to definitely position the rotatable catch 48 and the spaced apart plates 12 and 14.

There is also positioned in the lower part of the base 16, of each of the plates 12 and 14, a bolt 60. There is positioned on this bolt 60 a rotatable lever 62. The bolt 60 runs through aligned passageways in the plates 12 and 14 and also through a passageway in the lower end of the rotatable lever 62. The rotatable lever 62 has a short leg 64, through which is passed the bolt 60, and a long leg 66. On the outer end of the long leg 66 there is a curved leg 68 which splits into two spaced-apart positioning legs 70. Also, in the inner part of the long leg 66 there is a passageway 72 and which passageway extends into a passageway 74 in the outer part of the leg 66. The diameter of the passageway 72 is greater than the diameter of the passageway 74. Atthe junction of the passageways 72 and 74 in the long leg 66 there is a shoulder 76.

In the long leg 66, and near the junction with the short leg 64, there is a lateral passageway 78. In the lateral passageway 78 there are two spaced apart plungers 80. The lateral passageway 78 connects with the longitudinal passageway 72. There is positioned in the longitudinal passageway 72 a piston 82 and which piston 82 has a tapered end 83. The piston 82 connects with a pin 84 having an enlarged head 86. A spring 88, a resilient means 88, bears against the inner end or shoulder of the piston 82 and also against the shoulder 76 between the passageways 72 and 74. The spring 88 urges the piston 82 between the two plungers 80.

In FIGS. 1, 3, 4 and 5, there are illustrated various positions of the rotatable lever 62. In FIG. 3 it is seen that in the inner surfaces of the two spaced apart plates 12 and 14 that there are aligned recesses 90. These recesses 90 are for receiving the plungers and for holding the releasable hook in a completely closed position. Then, in FIG. 3 it is seen that to the right of the recesses there is a recess in the inner surface of each spaced apart plate 12 and 14, recess 92. With the plungers 80 in the recesses 92 the releasable hook is held in a partially open and also a partially closed position.

The positioning legs 70 position a release lever 96. In FIG. 5 it is seen that the positioning legs 70 are spaced apart and that a pin 98 runs between these legs 70. The release lever 96 is firmly positioned as the pin 98 also runs through a passageway in the release lever 96, as well as running through aligned passageways in the positioning legs 70. Then, the outer end of the release lever 96 splits into two legs 100 and which legs 100 are on each side of the pin 84. The head 86 of the pin 84 is of sufficiently large diameter that the legs 100 cannot slip over the head 86. A pin 102 runs between the legs 100 and outside of the pin 84 so that the release hook 96 is definitely positioned so as to encompass the pin 84.

It is possible by pulling on a cord or rope 104 to rotate the release lever 96, in FIG. 1, in a clockwise direction so as to move the pin 84 partially out of the passageways 74 and 72 and thereby move the piston 82 so as to be partially or completely out of contact with the plungers 80. This allows the plungers 80 to move away from the recesses 90 or the recesses 92 in the inner surfaces of the spaced apart plates 12 and 14.

A connecting rod 108 connects the short leg 64 of the rotatable lever 62 and the upper part of the rotatable catch 48. In FIG. 6 it is seen that the rotatable catch 48 has a recess 112 for receiving the connecting rod 108. There is a lateral passageway 114 in the upper part of the rotatable catch 48, in fact, two lateral passageways and which two lateral passageways are aligned. A pin 116 is positioned in these two lateral passageways and run through a passageway in the end of the connecting rod 108.

Now, in FIG. 7, it is seen that the outer end of the short leg 64 of the rotatable lever 62 has a recess 120 so as to have the lower end of the short leg 64 divided into two parts. There is a lateral passageway 122 in each part and a pin 124 is positioned in the two lateral passageways 122. These two lateral passageways 122 are aligned. Also, there is a passageway in the end of the connecting rod 108. The pin 124 runs through this lateral passageway in the connecting rod 108 and is also positioned in the two lateral passageways 122.

The connecting rod 108 is free to rotate around the pin 116 and is also free to rotate around the pin 124. Therefore, upon rotating the lever 62 the connecting rod 108 rotates around the two pins 116 and 124 and the rotatable catch 48 rotates around the bolt or pin 46.

There is a masked head 130 having an outwardly projecting end 132 with flat sides or flat surfaces 134. Then, the masked head has a main body portion 136 having an end in a general semicircular. The body portion 132 is somewhat smaller than the body portion 136 and at the junction of the body portion 132 and the body portion 136 there are two substantially straight shoulders 138. The shoulders 138 are on the outer edges of the body 136. In the body 132 there is a passageway 140. In the body 136 there is a passageway 142. The passageways 140 and 142 are substantially at right angles to each other.

There is a mounting bracket 146 and which mounting bracket in a side view, seen FIG. 1, is of a generally U- configuration with a base 148, an upper leg 150 and a lower leg 152. Also, as is seen in FIG. 2, there are side flanges 154. In each of the legs 150 and 152 there is a passageway 156. The passageways 156 in the legs and 152 are aligned.

The crosshead 130 is positioned on the mounting bracket 146 by means of a pin 160 passing through the passageways 156 in the legs 150 and 152 and also passing through the passageway 142 in the crosshead 130. In FIGS. 1 and 2, it is seen that the crosshead 130 is free to rotate with respect to the bracket 146 and can rotate around the pin 160.

The mounting bracket 146 is attached to a dock 164 or a barge 164. The lag bolts 166 project through the flanges 154 and into the dock or barge 164 so as to firmly attach the mounting bracket 146 to the dock or barge.

In the ends 20 of the plates 12 and 14, there are passageways 168. These passageways 168 are aligned. A bolt 170 projects through the passageways 168 in the plates 12 and 14 and also projects through the passageway 140 in the crosshead 130. Naturally, there is a nut 172 on the end of the bolt 170. This secures the releasable hook 10 onto the crosshead 130.

In FIG. 1, it is seen that the substantially straight end 24 of each plate 12 and 14 bears against the shoulder 138 of the crosshead 130. This limits the counterclockwise rotation of the releasable hook 10 with respect to the crosshead 130 and also with respect to the mounting bracket 146. However, the curved shoulder 26 allows the releasable hook 10 to be rotated upwardly and in a clockwise direction. Therefore, it is seen that due to the rotation of the crosshead 130 with respect to the mounting bracket 146, this rotation is approximately in a horizontal direction, and due to the rotation of the releasable hook 10 with respect to the crosshead 130, a rotation of approximately 75 90 in the vertical direction.

In FIGS. 1 and 4, it is seen that the frame or plates 12 and 14 near the end 18, and on the upper surface, have a curving surface 180.

In FIG. 1, that with the end of the second leg 30 in the recess 50 of the rotatable catch 48 the first leg 28 is positioned relatively close to the curved surface 180 and that the end 34 of this first leg 28 is touching or positioned very close to the rotatable lever 62 so as to form, in essence, a closed fastening means or hook and with the line or cable 182 positioned at the junction of the legs 28 and 30 or at the junction of the legs 28 and the curved surface 180 of the end 18. In this position, it is seen, see FIGS. 1, 3 and 5, that the plungers 80 are in the recesses 90 and the plates 12 and 14 and that the piston 82 is between the plungers 80 so as to firmly lock these plungers in position and to lock the rotatable catch 48 on the end of the leg 30.

By pulling the cord 104 the piston 82 is removed from between the plungers 80 and the U-shaped hook 26, due to the pull of the line 182, is able to rotate in a counterclockwise direction. Also, the rotatable catch 48 and the lever arm 62 rotate in a clockwise direction. Now, referring to FIG. 1, see the phantom line of the lever arm in FIG. 1, the plungers 80 will be in the recesses 92 in the plates 12 and 14 with the piston 82 between the plungers 80 so as to firmly lock the plungers in position and to firmly lock the lever arm 62 in position. Also, the rotatable catch 48 is firmly locked, see the phantom line of FIG. 48 in FIG. 1, so that the U- shaped hook 26 is partially open, or partially closed. Then, again pulling the cord 104, the piston 82 is removed between the two plungers 80 and the pull of the line 182, will further rotate the U-shaped hook 26 to assume the position as illustrated in FIG. 4. In this position, the line 182 is free to move out of and between the legs 28 and 30 of the U-shaped hook 26.

With the releasable hook in the position as illustrated in FIG. 4, it is seen that the piston 82 is no longer between the plungers 80 so as to force the plungers 8t) into recesses in the surfaces of the plates 12 and 14. In this regard, see FIG. 7 and FIG. 4. The plungers 80 are not in recesses in the inner surfaces of the plates 12 and 14 but are bearing against the inner surfaces of the plates 12 and 14. It is possible to rotate the lever arm with the plungers in these positions. In FIG. 4, it is seen that the tapered end 83 is between the plungers 80 but that the size of the tapered end 83 is not sufficient to strongly force the plungers 80 outwardly. The purpose of the tapered end 83 is to make it possible for the piston 82 to easily move between the plungers 80 when the plungers are near recesses 90 and/or 92.

Although in this description there is mentioned a U- shaped hook 26, the releasable hook is composed of the first leg 28 in conjunction with the upper curved surface 180 of the end 18. By releasing the rotatable catch 48, see FIG. 1, the U-shaped hook 26 is allowed to rotate around the bolt 40. With the release of the rotatable catch 48 the end 36 of the second leg 30 rotates in a counterclockwise direction and out of the recess 50 in the rotatable catch 48. The pull of the line, be a chain or a rope or a cable, will cause the U-shaped hook 26 to rotate in a counterclockwise direction and assume a position similar to that in FIG. 4 so that the line 182 can be freed from the releasable hook 10. By way of recapitulation, the second leg 30 and its end 36 function with the rotatable catch 48 and the recess 50 to lock the U-shaped hook 26 in such a position that the first leg 28 is positioned near the curved surface 1800f the frame, the plates 12 and 14, and the end 36 of the first leg 28 is positioned near the rotatable lever arm 62 so as to form a closed enclosure. The first leg 28 and the curved surface 180 of the frame, plates 12 and 14, form a releasable. hook. This releasable hook firmly positions the line 182 until the catch 48 is moved away from the end 36 of the first leg 28 so as to allow the line 182 to escape from the releasable book 10.

Another important feature of the releasable hook is the loading feature. In regard to the loading feature, the reader is directed to look at FIG. 1, the phantom line of the rotatable lever and also the phantom line of the rotatable catch 48. In FIG. 1, and with respect to the phantom lines for the rotatable lever 62, it is seen that there is a space between the end 34 of the first leg 28 and the rotatable lever 62. Also, the plungers 80 are positioned in the recesses 92 in the inside surfaces of the plates 12 and 14. Now, with the plungers 80 in the recesses 92, the rotatable lever 62 is locked in the position as illustrated by the phantom lines of FIG. 1. Also, the rotatable catch 48 is rotated slightly in a clockwise direction, in correspondence with the rotation of the rotatable lever 62 in a clockwise direction, and the end 36 of the second leg 30 is positioned in the recess 50 in the rotatable catch 48. Further, the U-shaped hook 26 is rotated through a few degrees in the counterclockwise direction as contrasted with the position as illustrated by the solid lines of the U-shaped hook 26 6 in FIG. 1. With the space between the end 34 of the first leg 28 and the rotatable lever 62, remember the phantom lines, there is sufficient room to place the line 182 in the releasable hook, i.e., between the first leg 28 and the curved surface of the frame members 12 and 14. It is possible to move a large line 182, such as a 3 inch diameter line, so as to be in this position in the releasable hook. This position is known as the loading position for loading the releasable hook.

From the foregoing and having presented my invention, what I claim is:

1. A releasable hook, said releasable hook comprising:

a. a frame;

b. a generally U-shaped hook having a first leg and a second leg;

c. a first means mounting said U-shaped hook on saidframe so as to allow said hook to rotate with respect to said frame;

(I. a rotatable catch;

e. said rotatable catch having a recess for receiving the second leg;

f. a second means mounting said rotatable catch on said frame so as to allow said rotatable catch to rotate with respect to said frame;

g. a rotatable lever arm;

h. a third means mounting said rotatable lever arm on said frame so as to allow said rotatable lever arm to rotate with respect to said frame;

i. a fourth means connecting said rotatable catch and said rotatable lever arm;

j. a fifth means for positioning said rotatable lever arm and said rotatable catch with the second leg in said recess in said rotatable catch and with said first leg positioned near but spaced apart from said frame so that in effect said first leg and said frame form said releasable hook;

k. said fifth means capable of being moved to allow said rotatable lever arm to be rotated so as to rotate said rotatable catch out of engagement with said second leg to allow said first leg to rotate away from said frame to open said releasable hook;

I. said fifth means comprising a locking mechanism for positioning said rotatable lever arm;

m. said fifth means comprising a lateral passageway in said lever arm and a longitudinal passageway in said lever arm;

11. said lateral passageway connecting with said longitudinal passageway;

o. a plunger in said lateral passageway;

p. a piston in said longitudinal passageway;

q. said piston when in contact with said plunger forcing said'plunger against said frame; and,

r. means to move said piston so that piston does not force said plunger against said frame.

2. A releasable hook, said releasable hook comprising:

a. a frame;

b. a generally U-shaped hook having a first leg and a second leg;

c. a first means mounting said U-shaped hook on said frame so as to allow said hook to rotate with respect to said frame;

d. a rotatable catch; 1

e. said rotatable catch having a recess for receiving the second leg;

f. a second means mounting said rotatable catch on said frame so as to allow said rotatable catch to rotate with respect to said frame;

g. a rotatable lever arm;

h. a third means mounting said rotatable lever arm on said frame so as to allow said rotatable lever arm to rotate with respect to said frame;

i. a fourth means connecting said rotatable catch and said rotatable lever arm;

j. a fifth means for positioning said rotatable lever arm and said rotatable catch with the second leg in said recess in said rotatable catch and with said first leg positioned near but spaced apart from said frame so that in effect said first leg and said frame form said releasable hook;

k. said fifth means capable of being moved to allow said rotatable lever arm to be rotated so as to rotate said rotatable catch out of engagement with said second leg to allow said first leg to rotate away from said frame to open said releasable hook;

I. said frame comprising two spaced apart plates;

m. said fifth means comprising a locking mechanism for positioning said rotatable lever arm;

n. said fifth means comprising a lateral passageway in said lever arm and a longitudinal passageway in said lever arm;

0. said lateral passageway connecting with said longitudinal passageway;

p. two plungers in said lateral passageway;

q. a first recess in the inner surface of each plate for receiving one of said plungers;

r. a movable piston in said longitudinal passageway;

s. means to move said piston between said two plungers to force said plungers against said spaced apart plates;

t. means to move said piston so that said piston does not force said plunger against said frame;

u. with said plungers in said first recesses said rotatable lever arm and said rotatable catch are firmly positioned with the second leg in said recess in said rotatable catch and with the first leg positioned near but spaced apart from said frame and with the end of said first leg near said lever arm to form an enclosure and said releasable hook; and,

v. with said piston not forcing said two plungers against vsaid spaced apart plates said U-shaped hook is free to rotate with respect to said frame.

3. A releasable hook according to claim 2 and comprising:

a. a second recess in the inner surface of each plate for receiving one of said plungers; and,

b.vwith said plunger in said second recesses, said rotatable lever arm and said rotatable catch are firmly positioned with the second leg in said recess in said rotatable catch with the first leg positioned near but spaced apart from said frame and with the end of said first leg positioned away from said lever arm to have said releasable hook in a partially open position.

4. A releasable hook according to claim 3 and comprising:

a. a pin connecting with said movable piston;

b. said pin being in said longitudinal passageway;

c. a resilient means urging said movable piston between said two plungers; and,

d. a means for moving said pin and said movable piston away from said two plungers.

5. A releasable hook, said releasable hook comprising:

a. a frame;

b. a generally U-shaped hook having a first leg and a second leg;

c. a first means mounting said U-shaped hook on said frame so as to allow said hook to rotate with respect to said frame;

d. a rotatable catch;

e. said rotatable catch having a recess for receiving the second leg;

f. a second means mounting said rotatable catch on said frame so as to allow said rotatable catch to rotate with respect to said frame;

g. a rotatable lever arm;

h. a third means mounting said rotatable lever arm on said frame so as to allow said rotatable lever arm to rotate with respect to said frame;

i. a fourth means connecting said rotatable catch and said rotatable lever arm;

j. a fifth means for positioning said rotatable lever arm and said rotatable catch with the second leg in said recess in said rotatable catch and with said first leg positioned near but spaced apart from said frame so that in effect said first leg and said frame form said releasable hook;

k. said fifth means capable of being moved to allow said rotatable lever arm to be rotated so as to rotate said rotatable catch out of engagement with said second leg to allow said first leg to rotate away from said frame to open said releasable hook;

1. said frame on that end away from said U-shaped hook has a curved upper shoulder and a straight end;

m. a crosshead;

n. said crosshead having a substantially straight shoulder;

o. a means connecting together said frame and said crosshead so that said frame can rotate around said means with respect to said frame;

p. said curved upper shoulder of said frame allowing said frame to rotate with respect to said crosshead; and,

q. said straight end of said frame when in contact with said substantially straight shoulder of said crosshead preventing rotation of said frame with respect to said crosshead.

6. A releasable hook according to claim 5 and com prising: 1

a. a mounting bracket; and,

b. a means connecting together said crosshead and said mounting bracket and allowing rotation of said mounting bracket and said crosshead with respect to each other.

7. A releasable hook according to claim 2 and comprising:

a. each of said two spaced apart plates of said frame on that end away from said U-shaped hook has a curved upper shoulder and a straight end;

b. a crosshead;

c. said crosshead having a substantially straight shoulder;

d. a means connecting together said frame and said crosshead so that said frame can rotate around said means with respect to said frame;

e. said curved upper shoulder of said frame allowing said frame to rotate with respect to said crosshead; and, v

f. said straight end of said frame when in contact with said substantially straight shoulder of said crosshead preventing rotation of said frame with respect b. a means connecting together said crosshead and to said crosshead. said mounting bracket and allowing rotation of said 8. A releasable hook according to claim 7 and commounting bracket and said crosshead with respect prising: to each other.

a. a mounting bracket; and, v 

1. A releasable hook, said releasable hook comprising: a. a frame; b. a generally U-shaped hook having a first leg and a second leg; c. a first means mounting said U-shaped hook on said frame so as to allow said hook to rotate with respect to said frame; d. a rotatable catch; e. said rotatable catch having a recess for receiving the second leg; f. a second means mounting said rotatable catch on said frame so as to allow said rotatable catch to rotate with respect to said frame; g. a rotatable lever arm; h. a third means mounting said rotatable lever arm on said frame so as to allow said rotatable lever arm to rotate with respect to said frame; i. a fourth means connecting said rotatable catch and said rotatable lever arm; j. a fifth means for positioning said rotatable lever arm and said rotatable catch with the second leg in said recess in said rotatable catch and with said first leg positioned near but spaced apart from said frame so that in effect said first leg and said frame form said releasable hook; k. said fifth means capable of being moved to allow said rotatable lever arm to be rotated so as to rotate said rotatable catch out of engagement with said second leg to allow said first leg to rotate away from said frame to open said releasable hook; l. said fifth means comprising a locking mechanism for positioning said rotatable lever arm; m. said fifth means comprising a lateral passageway in said lever arm and a longitudinal passageway in said lever arm; n. said lateral passageway connecting with said longitudinal passageway; o. a plunger in said lateral passageway; p. a piston in said longitudinal passageway; q. said piston when in contact with said plunger forcing said plunger against said frame; and, r. means to move said piston so that piston does not force said plunger against said frame.
 2. A releasable hook, said releasable hook comprising: a. a frame; b. a generally U-shaped hook having a first leg and a second leg; c. a first means mounting said U-shaped hook on said frame so as to allow said hook to rotate with respect to said frame; d. a rotatable catch; e. said rotatable catch having a recess for receiving the second leg; f. a second means mounting said rotatable catch on said frame so as to allow said rotatable catch to rotate with respect to said frame; g. a rotatable lever arm; h. a third means mounting said rotatable lever arm on said frame so as to allow said rotatable lever arm to rotate with respect to said frame; i. a fourth means connecting said rotatable catch and said rotatable lever arm; j. a fifth means for positioning said rotatable lever arm and said rotatable catch with the second leg in said recess in said rotatable catch and with said first leg positioned near but spaced apart from said frame so that in effect said first leg and said frame form said releasable hook; k. said fifth means capable of being moved to allow said rotatable lever arm to be rotated so as to rotate said rotatable catch out of engagement with said second leg to allow said first leg to rotate away from said frame to open said releasable hook; l. said frame comprising two spaced apart plates; m. said fifth means comprising a locking mechanism for positioning said rotatable lever arm; n. said fifth means comprising a lateral passageway in said lever arm and a longitudinal passageway in said lever arm; o. said lateral passageway connecting with said longitudinal passageway; p. two plungers in said lateral passageway; q. a first recess in the inner surface of each plate for receiving one of said plungers; r. a movable piston in said longitudinal passageway; s. means to move said piston between said two plungers to force said plungers against said spaced apart plates; t. means to move said piston so that said piston does not force said plunger against said frame; u. with said plungers in said first recesses said rotatable lever arm and said rotatable catch are firmly positioned with the second leg in said recess in said rotatable catch and with the first leg positioned near but spaced apart from said frame and with the end of said first leg near said leVer arm to form an enclosure and said releasable hook; and, v. with said piston not forcing said two plungers against said spaced apart plates said U-shaped hook is free to rotate with respect to said frame.
 3. A releasable hook according to claim 2 and comprising: a. a second recess in the inner surface of each plate for receiving one of said plungers; and, b. with said plunger in said second recesses, said rotatable lever arm and said rotatable catch are firmly positioned with the second leg in said recess in said rotatable catch with the first leg positioned near but spaced apart from said frame and with the end of said first leg positioned away from said lever arm to have said releasable hook in a partially open position.
 4. A releasable hook according to claim 3 and comprising: a. a pin connecting with said movable piston; b. said pin being in said longitudinal passageway; c. a resilient means urging said movable piston between said two plungers; and, d. a means for moving said pin and said movable piston away from said two plungers.
 5. A releasable hook, said releasable hook comprising: a. a frame; b. a generally U-shaped hook having a first leg and a second leg; c. a first means mounting said U-shaped hook on said frame so as to allow said hook to rotate with respect to said frame; d. a rotatable catch; e. said rotatable catch having a recess for receiving the second leg; f. a second means mounting said rotatable catch on said frame so as to allow said rotatable catch to rotate with respect to said frame; g. a rotatable lever arm; h. a third means mounting said rotatable lever arm on said frame so as to allow said rotatable lever arm to rotate with respect to said frame; i. a fourth means connecting said rotatable catch and said rotatable lever arm; j. a fifth means for positioning said rotatable lever arm and said rotatable catch with the second leg in said recess in said rotatable catch and with said first leg positioned near but spaced apart from said frame so that in effect said first leg and said frame form said releasable hook; k. said fifth means capable of being moved to allow said rotatable lever arm to be rotated so as to rotate said rotatable catch out of engagement with said second leg to allow said first leg to rotate away from said frame to open said releasable hook; l. said frame on that end away from said U-shaped hook has a curved upper shoulder and a straight end; m. a crosshead; n. said crosshead having a substantially straight shoulder; o. a means connecting together said frame and said crosshead so that said frame can rotate around said means with respect to said frame; p. said curved upper shoulder of said frame allowing said frame to rotate with respect to said crosshead; and, q. said straight end of said frame when in contact with said substantially straight shoulder of said crosshead preventing rotation of said frame with respect to said crosshead.
 6. A releasable hook according to claim 5 and comprising: a. a mounting bracket; and, b. a means connecting together said crosshead and said mounting bracket and allowing rotation of said mounting bracket and said crosshead with respect to each other.
 7. A releasable hook according to claim 2 and comprising: a. each of said two spaced apart plates of said frame on that end away from said U-shaped hook has a curved upper shoulder and a straight end; b. a crosshead; c. said crosshead having a substantially straight shoulder; d. a means connecting together said frame and said crosshead so that said frame can rotate around said means with respect to said frame; e. said curved upper shoulder of said frame allowing said frame to rotate with respect to said crosshead; and, f. said straight end of said frame when in contact with said substantially straight shoulder of said crosshead preventing rotation of said frame with respect tO said crosshead.
 8. A releasable hook according to claim 7 and comprising: a. a mounting bracket; and, b. a means connecting together said crosshead and said mounting bracket and allowing rotation of said mounting bracket and said crosshead with respect to each other. 